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Oncogenic Kras requires simultaneous PI3K signaling to induce ERK activation and transform thyroid epithelial cells

Kelly A Miller1, Nicole Yeager, Kristen Baker

  • 1Human Genetics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA.

Cancer Research
|April 9, 2009
PubMed

Insights

Activating both phosphatidylinositol-3-kinase (PI3K) and Ras signaling pathways simultaneously drives thyroid cancer development and metastasis in mice. Targeting both pathways offers a potential therapeutic strategy for follicular cell-derived thyroid cancers.

Area of Science:

  • Molecular Oncology
  • Endocrine Neoplasia
  • Cancer Signaling Pathways

Background:

  • Thyroid tumors frequently exhibit mutations activating phosphatidylinositol-3-kinase (PI3K) and Ras signaling.
  • The individual and combined roles of these activated pathways in thyroid tumorigenesis remain incompletely understood.

Purpose of the Study:

  • To investigate the in vivo contribution and interaction of PI3K and Ras signaling in thyroid follicular cell transformation.
  • To determine the oncogenic potential of simultaneous PI3K and Ras pathway activation in the thyroid epithelium.

Main Methods:

  • Utilized a genetically engineered mouse model with targeted Kras oncogenic mutation and Pten deletion in thyroid epithelium.
  • Analyzed the effects of dual pathway activation on thyroid follicular cell transformation, invasion, and metastasis.
  • Assessed molecular mechanisms including MAPK/ERK signaling and cyclin D1 regulation.

Main Results:

  • Neither PI3K nor Ras activation alone was sufficient for thyroid follicular cell transformation.
  • Simultaneous activation of both pathways resulted in highly oncogenic follicular carcinomas with invasive and metastatic properties.
  • PI3K activation counteracted Kras-induced feedback, reducing MAPK/ERK signaling, while both pathways synergistically increased cyclin D1 mRNA.

Conclusions:

  • Co-activation of PI3K and Ras signaling is a critical driver of aggressive thyroid cancer.
  • Combined inhibition of PI3K and MAPK pathways effectively suppressed tumor cell growth in vitro.
  • Dual targeting of PI3K and MAPK pathways presents a promising therapeutic strategy for advanced thyroid cancer.

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